Impact of cardiorespiratory fitness and diabetes status on cardiovascular disease and all-cause mortality: An NHANES retrospective cohort study

High cardiorespiratory fitness (CRF) is associated with decreased mortality in people with pre-diabetes (pre-DM) and diabetes mellitus (DM); however, the degree to which CRF attenuates the risk of cardiovascular disease (CVD)-related and all-cause mortality is unclear. Study objective: We examined the impact of CRF status on CVD-related morbidity and all-cause mortality in nonDM, Pre-DM, and DM populations. Design and setting: 13,968 adults from the Third US National Health and Nutrition Examination Survey (NHANES III) were stratified into non-DM, pre-DM, or DM groups based on HbA1c levels. VO2Max was calculated using the Fitness Registry and Importance of Exercise: A National Database (FRIEND) equation. Participants: Participants were categorized into tertiles of VO2Max; first VO2Max tertile was the lowest VO2Max and third VO2Max tertile was the highest. Main outcome measure(s): Cox regression was used to analyze the relationship between glycemic levels, VO2Max, and CVD-related and all-cause mortality. Results: Those with DM in the highest fitness tertile had CVD (HR 0.13; 95 % CI 0.06, 0.27; p G 0.0001) and all cause (HR 0.28; 95 % CI 0.21, 0.38; p G 0.0001) mortality rates as low or lower than those with pre-DM (CVD HR 1.02; 95 % CI 0.78, 1.33 p G 0.892; all cause HR 0.96; 95 % CI 0.83, 1.12; p G 0.5496) or non-DM (CVD HR 0.65; 95 % CI 0.52, 0.80; p G 0.0001; all cause HR 0.61; 95 % CI 0.55, 0.68; p G 0.0001) at lower fitness levels. Regardless of DM status, there was lower all-cause mortality with higher CRF levels. Conclusions: Higher fitness levels in DM individuals are associated with total and CVD mortality rates as low or lower than those without DM with lower fitness.